1. Field of the Invention
The present invention relates to a laminated coil and, more specifically, to an open magnetic path type laminated coil having an excellent direct current (DC) superposition characteristic.
2. Description of the Related Art
An open magnetic path type laminated coil has been proposed as a known laminated coil in order to prevent a sudden decrease in the inductance value due to magnetic saturation inside a magnetic body. As described in Japanese Examined Patent Application Publication No. 1-35483, an open magnetic path type laminated coil includes a non-magnetic layer provided inside a laminated coil including magnetic layers. According to the structure of the open magnetic path type laminated coil, magnetic flux leaks from portions in the magnetic layers to the outside of the laminated coil, making it difficult for magnetic saturation to occur inside the magnetic body. As a result, reduction in inductance caused by a direct current is reduced, and the DC superposition characteristic is improved.
Although the open magnetic path type laminated coil according to Japanese Examined Patent Application Publication No. 1-35483 has an excellent DC superposition characteristic, there is a problem in that the inductance characteristic is unsatisfactory. In other words, since the non-magnetic layer is disposed at a location along the path of magnetic flux, the magnetic flux is blocked, causing a reduction in inductance. To obtain the desired inductance, the inductance may be increased by increasing the number of coil turns. However, an increase in the number of coil turns causes the direct current resistance to be significantly increased.